Ru(II)(bpy)3-Cob(II)yrinat – ein binuklearer Photoredox-Photokatalysator. Synthese und Anwendung in der organischen Chemie

Abstract

The synthesis of the binuclear 'RuII-CoII' complex (5a) is described. Its two subunits consist of derivatives of RuII(bpy)3++ and cob(II)yrinate. 5a undergoes 7 one-electron redox processes in the potential range + 1.5 to–1.8 V (vs. SCE). Luminescence from the RuII(bpy)3? subunit is effectively reduced, however, the quenching mechanism has not been elucidated. Upon visible light irradiation and in presence of triethanolamine (TEOA), the formation of 'RuII-CoI' is observed. Using TEOA as an electron donor, the catalyst consumes formally two quanta of visible light to promote the endergonic reduction of an aliphatic alkyl halide. 5a has been used as a 'photoredox-photocatalyst' in the radical-type cyclisation of methyl 1-(3-bromopropyl)-4-oxocyclohexa-2,5-diene-1-carboxylate (8) to the corresponding indene derivative (9).